130 
Laboratory  Contributions. 
J  Am.  Jour.  Pharm 
\     March,  1884. 
and  are  also  found  in  the  stem  of  the  anomalous  Welwitschia  mira- 
bilis,  for  a  figure  of  which  see  "  De  Bary  Vergleichende  Anatomie,"  p. 
140.  There  is,  however,  this  difference  between  the  liquorice  root  and 
the  other  plants,  i.  e.  in  the  former  several  fibres  are  included  in  a 
single  crystal  sheath,  while  in  the  quebracho  and  welwitschia  there  is 
but  a  single  fibre. 
Mr.  Jesse  G.  Shoemaker  contributes  two  diagnostic  characters  in 
the  stems  and  roots  (say  one-fourth  of  an  inch  in  diameter)  of  Gelsemi- 
um  sempervirens,  which  so  far  as  seen  are  peculiar  in  their  association, 
Fig.  3. 
and  which  hence  are  of  positive  value.  The  first  is  derived  from  the 
medullary  rays.  These  usually  widen  in  a  marked  manner,  going 
from  the  centre  to  the  circumference,  being  sometimes  much 'more  than 
twice  as  broad  exteriorly  as  interiorly.  The  second  character  is  the 
tendency  of  the  pith  to  be  penetrated  by  several  plates  of  large,  thin- 
walled  cells,  which  divide  the  pith  more  or  less  perfectly  into  four 
portions.  This  latter  character,  though  as  far  as  observed  it  varies  con- 
siderably in  the  relations  of  the  large  cells  and  the  ordinary  pith  cells, 
is  always  present  and  plainly  enough  marked  to  serve  as  a  means  of 
diagnosis.  Tests  upon  this  point  have  been  made  on  both  fresh  and 
dry  specimens  received  at  different  times  from  different  places.  Figure  3 
illustrates  these  peculiarities,  magnified  about  400  diameters. 
